The present invention relates to rigid materials and especially rigid load bearing materials suitable for use as site foundations, roads, helicopter landing pads, aircraft runways, roofing, trench and waterway linings, in making repairs to pipeline and storage vessels, and the like, and to a process for preparing such materials.
The use of polyester resins is quite popular in the plastic industry for fabricating various parts, especially fiber-reinforced parts. In general, the advantages of polyester resins with glass fibers, for example, include lightweight combined with strength, low maintenance of cost, chemical resistance, thermal insulation, ease of forming into diverse shapes, and the like. However, partially cured polyester resins must be catalyzed before they can readily undergo further polymerization to a sufficient final cure.
After addition of a catalyst, polyester resins have a major disadvantage in that they are relatively unstable and have a short pot life of no more than one to two days at ambient temperatures. Moreover, there is a certain amount of complexity in material preparation prior to producing a satisfactory molding, particularly one with fiber reinforcement. For example, the problems related to the weighing, metering, and mixing of quantities of material, including small quantities of catalysts and the like, have not only required some knowledge of chemistry on the part of a fabricator, but the weighing of small quantities causes accurate resin preparation to be a complex and time-consuming process. If too much catalyst becomes mixed into the resin by error of weighing, metering, or calculation, the resulting molding cures too fast, warps, or displays inferior mechanical properties. At times, the resin may prematurely harden in the mixing container or feed-line and cause costly cleanup operations as well as materials loss. On the other hand, if too little catalyst is mixed into the resin, the resulting molding may never fully cure and experience premature failure.
Still further, certain resin catalysts such as organic peroxides are hazardous to store by themselves. Because of their oxidizing nature, they are apt to cause fires or explosions in molding shops.